Mother substrate and display panel having substrate with opening, and method of manufacturing the display panel

ABSTRACT

Provided is a mother substrate comprising a glass substrate including a plurality of cutting lines, an organic film overlapping the plurality of cutting lines on the glass substrate, and a plurality of cells spaced apart from each other with each of the plurality of cutting lines therebetween on the glass substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. § 119(a)to Korean Patent Application No. 10-2020-0098268 filed on Aug. 6, 2020in the Republic of Korea, and Korean Patent Application No.10-2021-0082029 filed on Jun. 24, 2021 in the Republic of Korea, theentire contents of all these applications being expressly incorporatedherein by reference into the present application.

BACKGROUND 1. Field

The present disclosure relates to a mother substrate, a display panel,and a method of manufacturing the same.

2. Discussion of Related Art

An electroluminescent display device is classified into an inorganiclight emitting display device and an organic light emitting displaydevice depending on the material of a light emitting layer. The organiclight emitting display device of an active matrix type includes anOrganic Light Emitting Diode (hereinafter referred to as “OLED”) thatemits light by itself, and has an advantage that the response speed isfast, and the luminous efficiency, luminous and viewing angle are large.

In the organic light emitting display device, an OLED is formed on eachof the pixels. The organic light emitting display device has a highresponse speed, excellent luminous efficiency, luminous, viewing angle,and the like, and is capable of expressing black gradation in completeblack, thereby providing excellent contrast ratio and colorreproduction.

The organic light emitting display device does not require a backlightunit, and can be implemented on a plastic substrate, which is a flexiblematerial, a thin glass substrate, or a metal substrate. Therefore, aflexible display can be implemented as the organic light emittingdisplay device.

In the case of a flexible display, the size of the screen can be variedby winding, folding, and bending a flexible panel. The flexible displaycan be implemented as a rollable display, a foldable display, a bendabledisplay, a slidable display, or the like. Such flexible displays can beapplied to not only mobile devices such as smartphones and tablet PCs,but also to TVs, vehicle displays, and wearable devices, and theirapplication fields are expanding.

The flexible display can implement a Bezel bended display in which abezel region is minimized by folding a non-display region using aflexible panel structure. In addition, the flexible display can becoupled to the information device in a structure capable of varying thesize of the screen. Since the information device employs a flexibledisplay to increase the size of the screen, a multi-tasking is possibleby executing two or more applications or contents.

SUMMARY OF THE INVENTION

The flexible substrate used in a flexible display can be made of aflexible material, for example, a polyimide (PI) film substrate. In amanufacturing process of a flexible display panel, a circuit layer, anemitting element and the like can be formed on the PI film in a statewhere a carrier substrate having high rigidity and heat resistance isbonded under the PI film substrate. Since the carrier substrate is onlyneeded in the manufacturing process, after all the layers necessary fordriving the pixels are formed on the PI film, the carrier substrate canbe separated from the PI film substrate The carrier substrate and the PIfilm substrate can be separated by a laser lift off process using alaser equipment.

In the manufacturing process of the flexible display panel, themanufacturing cost can be rather high due to expensive laser equipment,and defects may occur during subsequent processing due to foreignmatters and roughness of the surface of the PI film when the PI filmsubstrate is peeled off by irradiating a laser on the entire surface ofthe substrate.

In addition, a folding part can be configured using an organic materialso that the existing flexible display panel is flexibly bent. In thiscase, the stiffness of the folding portion can be weak, such that creaseor hinge stains can be seen.

An object of the present disclosure is to address the aforementionedneeds and/or other limitations associated with the related art.

In a mother substrate according to an embodiment of the disclosure, themother substrate comprises a glass substrate including a plurality ofcutting lines; an organic film overlapping the plurality of cuttinglines on the glass substrate; and a plurality of cells spaced apart fromeach other with each of the plurality of cutting lines therebetween onthe glass substrate.

The organic film can overlap the plurality of cells and the plurality ofcutting lines.

The glass substrate can further include at least one bending linedisposed on each of the plurality of cells. The organic film can includea first organic film disposed on the glass substrate to overlap acutting line between neighbored cells of the plurality of cells, and asecond organic film disposed on the glass substrate to overlap the atleast one bending line.

Each of the cells can comprise a circuit layer disposed on the glasssubstrate to drive a pixel; a light emitting element layer including afirst electrode on the circuit layer, a bank disposed on the firstelectrode to define a light emitting area, an organic compound layer onthe first electrode in the light emitting area, and a second electrodeon the organic compound layer; an encapsulation layer covering the lightemitting element layer; and a polarizing plate disposed on theencapsulation layer. The organic film light can be disposed between theglass substrate and the circuit layer, and the organic layer and thebank include a same material.

The organic film and the polarizing plate can be sequentially stacked onthe glass substrate between adjacent cells to overlap the plurality ofcutting lines.

The first and second organic films can include a polyimide film.

The glass substrate can include a first opening exposing the firstorganic layer at positions overlapping the plurality of cutting lines; asecond openings exposing the second organic layer at positionsoverlapping the at least one bending line, and a coating layer isdisposed on a rear surface of the glass substrate and at least a portionof the first and second openings.

In a display panel according to an embodiment of the disclosure, thedisplay panel comprises a glass substrate; a circuit layer disposed onthe glass substrate to drive a pixel; a light emitting element layerincluding a light emitting element which includes a first electrode onthe circuit layer, an organic compound layer on the first electrode, anda second electrode on the organic compound layer; an encapsulation layercovering the circuit layer and the light emitting element layer; apolarizing plate on the encapsulation layer; and an organic film on theglass substrate.

The display panel can comprise a bank disposed on the first electrode todefine a light emitting area, wherein the organic film and the bankinclude a same material.

The display panel can comprise at least one bending line for folding thedisplay panel. The organic film can include a first organic film onedges of the glass substrate, and a second organic film disposed on theglass substrate to overlap the at least one bending line.

The glass substrate can include an opening exposing the second organiclayer at a position overlapping the at least one bending line.

A coating layer can be disposed on a rear surface of the glass substrateand at least a portion of the opening.

An edge sidewall of the glass substrate can include a wedge-shapedtapered surface, and a thickness of the sidewall becomes thinner as itgoes to the end of the sidewall.

The wedge-shaped tapered surface can protrude out of the circuit layer.

A length of the wedge-shaped tapered surface can be inverselyproportional to a thickness of the glass substrate.

In a method of manufacturing a display panel from a plurality of cellsdisposed on a mother glass substrate having an organic film according toan embodiment of the disclosure, the method comprises setting a cuttingline between adjacent cells of the plurality of cells; forming a mask onone surface of the mother glass substrate to cover regions other thanthe cutting line; etching the mother glass substrate exposed through themask to form a first opening in the mother glass substrate; removing themask; and cutting the organic film by irradiation laser to the organicfilm overlapping the cutting line to separate the plurality of cells.

The setting the cutting line can include setting at least one bendingline on which the display panel is folded in each of the plurality ofcells. The forming a mask ma include forming the mask so that the maskdoes not cover the at least one bending line; and etching the motherglass substrate exposed through the mask to form a second opening.

The organic film can include a first organic film disposed on the glasssubstrate to overlap a cutting line between neighbored cells of theplurality of cells; and a second organic film disposed on the motherglass substrate to overlap the at least one bending line.

The method can further comprise forming a coating layer on anothersurface of the mother glass substrate after removing the mask; andcutting the coating layer by irradiating the laser to the coating layerwhen the organic film is cut.

The etching the mother glass substrate can be implemented by a wetetching.

According to the embodiment, when the display panel is separated fromthe mother substrate, since a laser lift off process is not used, it ispossible to prevent defects due to foreign matters generated whenpeeling the PI film substrate and the roughness of the PI film surface,and reduce the cost.

According to the embodiment, since the display panel can be fabricatedbased on a glass substrate, it is possible to prevent the occurrence ofthe hinge stains of the folding region and enhance durability.

Furthermore, since the edge of the glass substrate can be fabricated ina wedge type, it is possible to prevent damage to the substrate.

The effects of the present disclosure are not limited to theabove-mentioned effects, and other effects that are not mentioned willbe clearly understood by those skilled in the art from the descriptionof the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the presentdisclosure will become more apparent to those of ordinary skill in theart by describing exemplary embodiments thereof in detail with referenceto the attached drawings, in which:

FIGS. 1 to 3 are views showing display panels including a bendingportion according to examples of the present disclosure;

FIG. 4 is a plan view of a display panel according to an embodiment ofthe present disclosure;

FIGS. 5A to 5D are cross-sectional views taken along line I-I′ in FIG. 4;

FIGS. 6A and 6B are cross-sectional views taken along line II-II′ inFIG. 4 ;

FIG. 7 is a plan view of a display panel according to another embodimentof the present disclosure;

FIGS. 8A to 8D are cross-sectional views taken along line I-I′ in FIG. 7;

FIGS. 9A and 9B are a cross-sectional view taken along line II-II′ inFIG. 7 ;

FIG. 10 is a plan view of a display panel according to anotherembodiment of the present disclosure;

FIGS. 11A to 11D are cross-sectional views taken along line I-I′ in FIG.10 ;

FIGS. 12A and 12B are cross-sectional view taken along line II-II′ inFIG. 10 ;

FIG. 13 is a cross-sectional view of a display panel according to anembodiment of the present disclosure;

FIG. 14 is an enlarged view of a sidewall portion A of a wedge-typesubstrate in FIG. 13 ;

FIG. 15 is a view showing a mother substrate according to an embodimentof the present disclosure;

FIG. 16 is a view illustrating a manufacturing process of a displaypanel according to an embodiment of the present disclosure;

FIG. 17 is a view illustrating a manufacturing process of a displaypanel according to an embodiment of the present disclosure;

FIG. 18 is a view illustrating a manufacturing process of a displaypanel according to another embodiment of the present disclosure;

FIG. 19 is a view illustrating a manufacturing process of a displaypanel according to another embodiment of the present disclosure;

FIG. 20 is a cross-sectional view taken along line C-C′ in FIG. 15 ;

FIG. 21 is a view illustrating an etching process of a mother glasssubstrate according to an embodiment of the present disclosure;

FIG. 22 is a cross-sectional photograph of a tapered surface formed on asidewall of the glass substrate 10;

FIG. 23 is a view showing various examples of a wedge-type sidewall of aglass substrate according to an embodiment of the present disclosure;

FIG. 24 is a cross-sectional photograph of a glass substrate showing atapered surface when the thickness of the substrate is reduced by anetching process of the glass substrate;

FIG. 25 is a block diagram illustrating an example of a display deviceaccording to an embodiment of the present disclosure;

FIG. 26 is a block diagram illustrating an example of a display deviceaccording to another embodiment of the present disclosure;

FIGS. 27A and 27B are views showing an example in which the displaydevice illustrated in FIG. 26 is folded;

FIG. 28 is a block diagram schematically showing the configuration of adrive IC according to an example of the present disclosure;

FIG. 29 is a circuit diagram showing an example of a pixel circuitaccording to an example of the present disclosure;

FIG. 30 is a diagram illustrating a method of driving the pixel circuitshown in FIG. 29 ; and

FIG. 31 is a cross-sectional view showing in detail a cross-section of adisplay panel according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The advantages and features of the present disclosure, and how toaccomplish them, will become apparent with reference to the embodimentsdescribed in detail below together with the accompanying drawings.However, the present disclosure is not limited to embodiments disclosedbelow, and can be implemented in various forms. These embodiments areprovided so that the present disclosure will be exhaustively andcompletely described, and will fully convey the scope of the presentdisclosure to those skilled in the art to which the present disclosurepertains. The present disclosure is only defined by the scope of theclaims.

Shapes, sizes, ratios, angles, number, and the like illustrated in thedrawings for describing embodiments of the present disclosure are merelyexemplary, and the present disclosure is not limited thereto. Likereference numerals designate like elements throughout. In the followingdescription, when a detailed description of well-known functions orconfigurations related to this document is determined to unnecessarilycloud a gist of the disclosure, the detailed description thereof will beomitted or may be provided briefly.

In the present disclosure, when the terms “include”, “have”, “comprisedof”, etc. are used, other components can be added unless “—only” isused. A singular expression can include a plural expression as long asit does not have an apparently different meaning in context.

In the explanation of components, even if there is no separatedescription, it is interpreted as including an error range.

In the description of position relationship, when a structure isdescribed as being positioned “on or above”, “under or below”, “next to”another structure, this description should be construed as including acase in which the structures contact each other as well as a case inwhich a third structure is disposed therebetween.

The terms “first”, “second”, etc. can be used to describe variouscomponents, but the components are not limited by such terms. The termsare used only for the purpose of distinguishing one component from othercomponents, and may not define order. For example, a first component canbe designated as a second component without departing from the scope ofthe present disclosure.

The features of various embodiments of the present disclosure can bepartially combined or entirely combined with each other, and can betechnically interlocking-driven in various ways. The embodiments can beindependently implemented, or can be implemented in conjunction witheach other.

Hereinafter, a “bending part” refers to a part that is bent in a displaypanel. The bending part can be a configuration that is bent in, forexample, a flexible display panel, can be a configuration that is bentto place a drive integrated circuit (IC) on a rear surface of a displaydevice, or can be a configuration that is bent to implement amulti-display. The bending part is not limited to these configurations

Hereinafter, various embodiments will be described in detail withreference to the accompanying drawings. All the components of eachdisplay device and each display panel according to all embodiments ofthe present disclosure are operatively coupled and configured.

In the embodiment, the display panel is fabricated based on a bendableglass film substrate. The glass film substrate can be a glass filmhaving a thickness of 0.2 mm or less. The glass film can be used as acommercially available reinforced glass film. Hereinafter, the glasssubstrate can be interpreted as a glass film substrate.

As shown in FIG. 1 , for example, a display panel 100 has a width in theX-axis direction, a length in the Y-axis direction, and a constantthickness in the Z-axis direction. The thickness of the display panel100 is thicker than that of the glass substrate because a circuit layerand a light emitting element layer can be disposed on the glasssubstrate. The width and length of the display panel 100 can be set tovarious design values according to the application field of the displaydevice. The display panel 100 can be fabricated in the shape of asubstantial rectangular plate as shown in FIG. 1 , but is not limitedthereto. For example, the display panel 100 can be fabricated as a panelhaving a different shape including a curved portion.

The display panel 100 can include non-bending portions 101 and 102 and abending portion 100 f disposed therebetween. The bending portion 100 fcan be formed as a bending line that crosses from one end to the otherend of the display panel along the length direction Y or the widthdirection X. The display panel 100 can be bent or folded around thebending portion 100 f by an external force. When the thickness of theglass substrate of the display panel 100 is thin, the display panel canbe flexibly bent with a sufficiently large curvature even by a smallforce.

The glass substrate of the bending portion 100 f can have a thicknesssmaller than that of the glass substrate of the non-bending portions 101and 102. Accordingly, the rigidity of the folding portion 100 f can beimproved, and a difference in refractive index between the bendingportion 100 f and the non-bending portions 101 and 102 can be reduced.

In the embodiment, an organic film including an organic material can beadded to at least a part of the bending portion 100 f so that thedisplay panel 100 can be easily bent in the bending portion 100 f. Asthe organic material, a resin material having good elasticity, forexample, one or a mixture of two or more of polyimide, polyurethane,acrylic, and silicone synthetic rubber can be applied. As an example ofsilicone synthetic rubber, a polydimethylsiloxane (PDMS) can be used.

The display panel 100 can include the bending portion 100 f and thenon-bending portions 101 and 102. At least one of the non-bendingportions 101 and 102 can include a display region in which an inputimage is reproduced. The non-bending portions 101 and 102 can havedifferent sizes.

Referring to FIG. 1 , the non-bending portions 101 and 102 can include afirst region 101 and a second region 102. In one embodiment, the firstregion 101 can include a pixel array in which an image is displayed, andthe second region 102 can include an IC mounting region in which a driveintegrated circuit (IC) for driving pixels is mounted. In anotherembodiment, the first region 101 can include a pixel array in which animage is displayed, and the second region 102 can include a pixel arrayin which at least a part of the image or preset additional informationis displayed.

When the second region 102 is used as an IC mounting region, the secondregion 102 can be bent at a high curvature in the bending portion 100 f,such that the second region 102 can be folded to a surface opposite tothe display surface on which the image is displayed. For example, thesecond region 102 can be folded behind the display surface of the firstregion 101. In other words, the second region 102 can be bent around thebending portion 100 f to form 180 degrees with the first region 101.

The examples of FIGS. 2 and 3 show bending portions 100 f disposedbetween three non-bending portions 101, 102, and 103 in a foldabledisplay. Each of the non-bending portions 101, 102, and 103 includes apixel array on which an image or information is displayed. The bendingportions 100 f can include glass and an organic film as described above.

FIG. 4 is a plan view of a display panel according to a first embodimentof the present disclosure.

FIGS. 5A to 5D are cross-sectional views taken along line I-I′ in FIG. 4.

FIGS. 6A and 6B are cross-sectional view taken along line II-II′ in FIG.4 . FIG. 6A is a cross-sectional view corresponding to FIG. 5A, and FIG.6B is a cross-sectional view corresponding to FIGS. 5B to 5C.

Referring to FIG. 4 , the display panel 100 according to the firstembodiment can include a bending portion 100 f and non-bending portions101 and 102. The non-bending portions 101 and 102 can include a firstregion 101 and a second region 102. The first region 101 can be adisplay region. The second region 102 can be an IC region in which adrive IC for driving the first region 101 is disposed. However, thepresent disclosure is not limited thereto, and as described above, thesecond region 102 can be a sub-display region. The bending portion 100 fcan form a bending line extending in one direction when viewed in a planview. The first region 101 and the second region can be bent at apredetermined angle around the bending line.

Hereinafter, a stacked structure of the display panel 100 according tothe first embodiment will be described in detail with reference to FIGS.5 A to 5D, 6A and 6B.

Referring to FIGS. 5A and 6A, the display panel 100 includes a glasssubstrate 10, an organic film 12 disposed on the glass substrate 10, acircuit layer 14 sequentially stacked on the organic film 12, and alight emitting element layer 16. The display panel 100 can furtherinclude an encapsulation layer 18 covering the circuit layer 14 and thelight emitting element layer 16, a polarizing plate 20 attached to theencapsulation layer 18 the by an adhesive agent 19, and a cover window22 on a polarizing plate 20. A touch screen in which touch sensors arearranged can be implemented on the display panel 100. For example, thetouch sensors can be disposed between the encapsulation layer 18 and thepolarizing plate 20.

The organic film 12 can be a film including one selected from the groupconsisting of a polyimide polymer, a polyester polymer, a siliconepolymer, an acrylic polymer, a polyolefin polymer, and a copolymerthereof. Since the polyimide has acid resistance and heat resistance, itcan be applied to a high temperature process of forming the circuitlayer 14 and the light emitting element layer 16. Since the circuitlayer 14 can be directly formed on the glass substrate 10 as in theembodiment to be described later, the organic film 120 can be omitted.

The circuit layer 14 can include data lines, a pixel circuit connectedto the gate lines and power supply lines, a gate driver connected to thegate lines, and the like. The pixel circuit and the gate driver caninclude circuit elements such as a thin film transistor (TFT), acapacitor, and the like. In order to reduce the tensile force and stressapplied to the circuit layer 14 when the bending portion 100 f is bent,the circuit layer 14 can include only wirings of the data lines, thegate lines, and the power supply lines in the bending portion 100 f.

The light emitting element layer 16 can include an OLED driven by adriving element of a pixel circuit. The OLED include an organic compoundlayer formed between an anode and a cathode. The organic compound layercan include a hole injection layer (HIL), a hole transport layer (HTL),an emission layer (EML), an electron transport layer (ETL), and anelectron injection layer (EIL), but is not limited thereto. When avoltage is applied to the anode and cathode of the OLED, holes passingthrough the hole transport layer (HTL) and electrons passing through theelectron transport layer (ETL) move to the emission layer (EML) to formexcitons, and as a result, the visible light is emitted from theemission layer (EML). The light emitting element layer 16 can furtherinclude a color filter array that selectively transmits red, green, andblue wavelengths.

The light emitting element layer 16 and the circuit layer 14 can becovered by a protective layer. The protective layer and theencapsulation layer 18 can be composed of an inorganic film made ofglass, metal, aluminum oxide (AlOx) or silicon (Si)-based material, orcan have a structure in which an organic film and an inorganic film arealternately stacked. The inorganic membrane blocks the penetration ofmoisture or oxygen. The organic film flattens the surface of theinorganic film. When the organic film and the inorganic film are stackedin multiple layers, the passage of moisture or oxygen is longer thanthat of a single layer, such that the penetration of moisture/oxygenaffecting the light emitting element layer 16 can be effectivelyblocked.

The polarizing plate 20 can be adhered to the encapsulation layer 18with an adhesive 19. The polarizing plate 20 can be bent and extended atan edge region except for a region where pads connected to an externalcircuit are formed, and be in contact with the upper surface of theorganic film 12. The polarizing plate 20 improves outdoor visibility ofthe display device. The polarizing plate 20 improves brightness ofpixels by reducing light reflected from the surface of the display panel100 and blocking light reflected from the metal of the circuit layer.The polarizing plate 20 can be implemented as a circular polarizingplate or a polarizing plate in which a linear polarizing plate and aphase delay film are bonded. A transparent cover window 22 can bedisposed on the polarizing plate 20.

The glass substrate 10 can be fabricated from plate-shaped alkali-freeglass or non-alkali glass. The glass substrate 10 can be divided into abending portion 100 f and non-bending portions 101 and 102. Thenon-bending portions 101 and 102 can include a first region 101 and asecond region 102.

In one embodiment, the first region 101 can include a pixel array onwhich an image is displayed, and the second region 102 can include an ICmounting region on which a drive integrated circuit (IC) for drivingpixels is mounted. In another embodiment, the first region 101 caninclude a pixel array in which an image is displayed, and at least apart of the second region 102 can include a pixel array in which animage or preset additional information is displayed. In FIG. 4 , thesecond region 102 is shown as an IC mounting region, but this is onlyexemplary.

Referring to FIG. 5A, the glass substrate 10 can be removed at a regionof the bending portion 100 f. In other words, the glass substrate 10 canbe formed to expose the organic film 12 located on the bending portion100 f to the rear surface of the display panel 100. The organic film 12can be a film including one selected from the group consisting of apolyester-based polymer, a silicone-based polymer, an acrylic polymer, apolyolefin-based polymer, and a copolymer thereof, as described above.

When the glass substrate 10 is removed at the bending portion 100 f,there can be an advantage of facilitating bending of the display panel100. For example, when only the organic film 12 is present at the lowerportion of the bending portion 100 f, it is possible to have anadvantage of minimizing stress applied to the display panel when thedisplay panel is bent.

Referring to FIGS. 5B to 5D and 6B, the display panel 100 can furtherinclude a coating layer 30 on a rear surface of the glass substrate 10shown in FIG. 5A.

As shown in FIG. 5B, the coating layer 30 can be formed on an entirerear surface of the glass substrate 10 to fill the opening of the glasssubstrate 10 exposing the organic layer 12. For example, the coatinglayer 20 can be formed on the entire rear surface of the substrateincluding the pad portion and the region adjacent to the pad portion. Inthis case, the polarizing plate 20 may not be formed on the pad portion.

As shown in FIG. 5C, the coating layer 30 can be formed on the rearsurface of the glass substrate 10 so as not to overlap the pat portionand the area adjacent to the pad portion of the glass substrate 10. Inthis case, the polarizing plate 20 may not be formed on the pad portion.

As shown in FIG. 5D, the coating layer 30 can be formed on the rearsurface of the glass substrate 10 so as not to overlap the pat portion,the area adjacent to the pad portion and the opening of the glasssubstrate 10. In this case, the polarizing plate 20 may not be formed onthe pad portion.

The coating layer 30 can be formed using a material having a goodstretchability in order to improve a bending characteristics of thedisplay panel. This is to prevent a decrease in rigidity when the glasssubstrate 10 is thinned. Alternatively, the coating layer 30 can beformed in the form of a reinforcing film capable of preventing scratcheson the glass substrate 10.

The coating layer 30 can be formed of an organic material including, forexample, a polyester-based polymer or an acrylic-based polymer.

FIG. 7 is a plan view of a display panel according to a secondembodiment of the present disclosure.

FIGS. 8A to 8D are cross-sectional views taken along line I-I′ in FIG. 7.

FIGS. 9A and 9B are cross-sectional views taken along line II-II′ inFIG. 7 . FIG. 9A is a cross-sectional view corresponding to FIG. 8 .FIG. 9B is a cross-sectional view corresponding to FIGS. 8B to 8D.

Hereinafter, the display panel 100 according to the second embodimentwill be described with reference to FIGS. 7 to 9B. Constituent elementsthat are substantially the same as those of the first embodiment aredenoted by the same reference numerals, and the description thereof willbe briefly described and the differences will be mainly described.

Referring to FIG. 7 , the display panel 100 according to the secondembodiment can include a bending portion 100 f and non-bending portions101 and 102. The non-bending portions 101 and 102 can include a firstregion 101 and a second region 102. The first region 101 can be adisplay region. The second region 102 can be an IC region in which adrive IC for driving the first region 101 is disposed. However, thepresent disclosure is not limited thereto, and as described above, thesecond region 102 can be a sub-display region. The display panel 100according to the second embodiment can include a part of the firstregion 101, the bending portion 100 f, and a partial organic film 13-1formed over the second region 102.

Hereinafter, a stacked structure of the display panel 100 according tothe second embodiment will be described in detail with reference toFIGS. 8A to 8D, and FIGS. 9A and 9B.

Referring to FIG. 8A and FIG. 9 , the display panel 100 includes a glasssubstrate 10, a circuit layer 14 sequentially disposed on the glasssubstrate 10, and a light emitting element layer 16. The display panel100 can further include an encapsulation layer 18 covering the circuitlayer 14 and the light emitting element layer 16, a polarizing plate 20attached to the encapsulation layer 18 by an adhesive agent 19, and acover window 22 on the polarizing plate 20.

The display panel 100 according to the second embodiment can furtherinclude a partial organic film 13-1 disposed between the glass substrate10 and the circuit layer 14. More specifically, the partial organic film13-1 can be disposed between the glass substrate 10 and the circuitlayer 14 on the second region 102, the bending portion 100 f, and aportion of the first region 101 adjacent to the bending portion 100 f.

The display panel 100 according to the second embodiment can furtherinclude a protective organic film 13-2 disposed between the glasssubstrate 10 and the circuit layer 14. More specifically, the protectiveorganic film 13-2 can be disposed along the edge of the first region 101on the glass substrate 10. The role of the protective organic film 13-2will be described later.

The polarizing plate 20 can be arranged similarly to that in the firstembodiment. For example, the polarizing plate 20 is bent and extended inthe remaining edge region except for the region where pads connected toan external circuit are formed, and to be disposed to contact the uppersurfaces of the partial organic film 13-1 and the protective organicfilm 13-2.

Similar to the display panel 100 according to the first embodiment, theglass substrate 10 can be removed at the bending portion 100 f. In otherwords, the glass substrate 10 can be formed to expose the partialorganic film 13-1 located on the bending portion 100 f to the rearsurface of the display panel 100. The partial organic film 13-1 can be afilm including one selected from the group consisting of apolyester-based polymer, a silicone-based polymer, an acrylic polymer, apolyolefin-based polymer, and a copolymer thereof.

When the glass substrate 10 is removed at the bending portion 100 f,there can be an advantage that the display panel 100 can be easily bent.For example, when only the partial organic film 13-1 is present at thelower portion of the bending portion 100 f, it is possible to have anadvantage of minimizing stress applied to the display panel when thedisplay panel is bent.

Referring to FIGS. 8B to 8D and 9B, the display panel 100 can furtherinclude a coating layer 30 on a rear surface of the glass substrate 10shown in FIG. 8A.

As shown in FIG. 8B, the coating layer 30 can be formed on an entirerear surface of the glass substrate 10 to fill the opening of the glasssubstrate 10 exposing the partial organic film 13-1. For example, thecoating layer 20 can be formed on the entire rear surface of thesubstrate including the pad portion and the region adjacent to the padportion. In this case, the polarizing plate 20 may not be formed on thepad portion.

As shown in FIG. 8C, the coating layer 30 can be formed on the rearsurface of the glass substrate 10 so as not to overlap the pat portionand the area adjacent to the pad portion of the glass substrate 10. Inthis case, the polarizing plate 20 may not be formed on the pad portion.

As shown in FIG. 8D, the coating layer 30 can be formed on the rearsurface of the glass substrate 10 so as not to overlap the pat portion,the area adjacent to the pad portion and the opening of the glasssubstrate 10. In this case, the polarizing plate 20 may not be formed onthe pad portion.

The material for forming the coating layer 30 and its function are thesame as those described in FIGS. 5B to 5D, and thus will be omitted toavoid overlapping description.

FIG. 10 is a plan view of a display panel according to a thirdembodiment of the present disclosure.

FIGS. 11A to 11D are cross-sectional views taken along line I-I′ in FIG.10 .

FIGS. 12A and 12B are cross-sectional views taken along line II-II′ inFIG. 10 . FIG. 12A is a cross-sectional view corresponding to FIG. 11A,and FIG. 12B is a cross-sectional view corresponding to FIGS. 11B to11D.

Hereinafter, a display panel 100 according to a third embodiment will bedescribed with reference to FIGS. 10 to 12B. Constituent elements thatare substantially the same as those of the first embodiment are denotedby the same reference numerals, and the description thereof will bebriefly described and the differences will be mainly described.

Referring to FIG. 10 , the display panel 100 according to the thirdembodiment can include a bending portion 100 f and non-bending portions101 and 102. The non-bending portions 101 and 102 can include a firstregion 101 and a second region 102. The first region 101 can be adisplay region. The second region 102 can be an IC region in which adrive IC for driving the first region 101 is disposed, but is notlimited thereto.

Hereinafter, a stacked structure of the display panel 100 according tothe third embodiment will be described with reference to FIGS. 11A to11D and FIGS. 12A and 12B.

Referring to FIGS. 11A and 12A, the display panel 100 includes a glasssubstrate 10, a circuit layer 14 sequentially disposed on the glasssubstrate 10, and a light emitting element layer 16. The display panel100 can further include an encapsulation layer 18 covering the circuitlayer 14 and the light emitting element layer 16, a polarizing plate 20attached to the encapsulation layer 18 the by an adhesive agent 19, anda cover window on a polarizing plate 20.

The display panel 100 according to the third embodiment can furtherinclude a protective organic film 13-2 disposed between the glasssubstrate 10 and the circuit layer 14. More specifically, the protectiveorganic film 13-2 can be disposed at the edge of the first region 101.The role of the protective organic film 13-2 will be described later.

The polarizing plate 20 can be arranged similarly to that in the firstembodiment. For example, the polarizing plate 20 is bent and extended inthe remaining edge region except for the region where pads connected toan external circuit are formed, and to be disposed to contact the uppersurfaces of the protective organic film 13-2.

Unlike the display panel 100 according to the first and secondembodiments, the display panel 100 according to the third embodiment maynot remove the glass substrate 10 at the bending portion 100 f. Even ifthe glass substrate 10 at the bending portion 100 f is not removed, whenthe glass substrate 10 is formed thin enough, it is possible to bendwith a sufficiently large curvature with only the glass substrate 10.The glass substrate 10 formed thinly can be flexibly bent and can haveacid resistance and heat resistance characteristics. Accordingly, in thethird embodiment, the circuit layer 14 can be directly mounted on theglass substrate 10 formed thinly.

As a modified example, in FIGS. 11A to 11D, the thickness of the glasssubstrate 10 of the bending portion 100 f and the thickness of the glasssubstrate 10 of the non-bending portions 101 and 102 can be formeddifferently. For example, in order to facilitate bending, the glasssubstrate 10 of the bending portion 100 f can be formed to be thinnerthan the glass substrate 10 of the non-bending portions 101 and 102.

The display panel 100 according to the third embodiment can furtherinclude a protective organic film 13-2 disposed between the glasssubstrate 10 and the circuit layer 14. More specifically, the protectiveorganic film 13-2 can be disposed along the edge of the first region 101and edges of the second region 102 and the bending portion 100 f on theglass substrate 10 as shown in FIG. 10 . The role of the protectiveorganic film 13-2 will be described later.

Referring to FIGS. 11B to 11D and 12B, the display panel 100 can furtherinclude a coating layer 30 on a rear surface of the glass substrate 10shown in FIG. 11A.

As shown in FIG. 11B, the coating layer 30 can be formed on an entirerear surface of the glass substrate 10 to fill the opening of the glasssubstrate 10 exposing the organic layer 12. For example, the coatinglayer 20 can be formed on the entire rear surface of the substrateincluding the pad portion and the region adjacent to the pad portion. Inthis case, the polarizing plate 20 may not be formed on the pad portion.

As shown in FIG. 11C, the coating layer 30 can be formed on the rearsurface of the glass substrate 10 so as not to overlap the pat portionand the area adjacent to the pad portion of the glass substrate 10. Inthis case, the polarizing plate 20 may not be formed on the pad portion.

As shown in FIG. 11D, the coating layer 30 can be formed on the rearsurface of the glass substrate 10 so as not to overlap the pat portion,the area adjacent to the pad portion and the opening of the glasssubstrate 10. In this case, the polarizing plate 20 may not be formed onthe pad part.

The material for forming the coating layer 30 and its function are thesame as those described in FIGS. 5B to 5D, and thus will be omitted toavoid overlapping description.

The display panel according to the above-described embodiment can beused as a flexible display panel. In this case, the glass substrate 10can be fabricated to a sufficiently thin thickness so that it can bebent at the required curvature of the application product.

The glass substrate 10 fabricated thinly can be flexible, but when animpact is applied to the edge sidewalls and corners, cracks can beoccurred or be damaged. In order to distribute the impact or stressapplied from the outside in a weak portion of the glass substrate 10fabricated thinly, the sidewall of the edge of the glass substrate 10can be processed in a wedge type.

FIG. 13 is a cross-sectional view of a display panel according to afourth embodiment of the present disclosure.

FIG. 14 is an enlarged view of a sidewall portion A of a wedge-typesubstrate in FIG. 13 .

The fourth embodiment of FIG. 13 is an embodiment of a display panel towhich a wedge-type substrate is applied, and the wedge-type glasssubstrate of FIG. 13 can be applied instead of the substrates of thefirst to third embodiments described above.

Referring to FIGS. 13 and 14 , the display panel 100 according to thefourth embodiment includes a glass substrate 10, a circuit layer 14stacked on the glass substrate 10, and a light emitting element layer16. The display panel 100 can further include an encapsulation layer 18covering the circuit layer 14 and the light emitting element layer 16, apolarizing plate 20, and a cover window 22. The display panel 100 canfurther include a touch sensor layer 13 disposed between theencapsulation layer 18 and the polarizing plate 20. Touch sensor wiringscan be formed connecting the touch sensors to the touch sensor layer 13and the touch sensors to the touch sensor driver.

It is preferable that the glass substrate 10 has a thin thickness, forexample, 200 μm or less so that it can be flexibly bent. As in theabove-described embodiment, the organic film 12 is disposed on the glasssubstrate 10, or the protective organic film 13-2 is disposed on theedge of the glass substrate 10. Alternatively, as in the above-describedembodiment, the partial organic film 13-1 can be disposed between thefirst region 101 and the second region 102 on the glass substrate 10,for example, on the bending portion 100 f.

The sidewall of the edge of the glass substrate 10 can be processed in awedge type. The sidewall of the corner portion where the two sides meeton the glass substrate 10 can also be processed in the wedge type. Thewedge type means a symmetrical shape in which each tapered surface ofthe upper half-thick portion and the lower half-thick portion of theglass substrate 10 is formed with respect to the thickness center REF ofthe glass substrate 10 as shown in FIG. 14 when viewed from the crosssection of the edge of the glass substrate 10. Accordingly, thethickness of the glass substrate 10 gradually decreases from the edge tothe sidewall due to the upper/lower symmetrical tapered surface 10 w.The tapered portion at the glass substrate 10 protrudes out of thecircuit layer 14, and the thickness becomes thinner toward the end ofthe sidewall of the glass substrate 10.

The coating layer 30 can be formed on the entire rear surface of theglass substrate 10. The coating layer 30 can reinforce rigidity when thewedge-type glass substrate 10 is thinly formed, and can preventscratches on the glass substrate 10.

Hereinafter, a method of manufacturing a display panel according to anembodiment will be described with reference to FIGS. 15 to 20 .

FIG. 15 is a view showing a mother substrate according to an embodimentof the present disclosure.

Referring to FIG. 15 , in the display panel 100 according to theembodiment, a process of forming a thin film in a plurality of cells1100 on a mother substrate 1000, which is a large glass substrate, issimultaneously formed. Hereinafter, for convenience of description, themother substrate 1000 according to the embodiment is referred to as amother glass substrate 1110. Here, one cell 1100 preferably can mean onedisplay panel.

A plurality of display panels 100 can be simultaneously manufactured ina multi-faceted process in order to reduce cost. First, a plurality ofcells 1100 can be formed on the mother substrate 1000. After the cells1100 are formed, a cutting line 1000 c can be set on the mothersubstrate 1000. Each of the cells 1100 can be separated (or cut) fromthe mother substrate 1000 with respected to the cutting line 1000 c toform the display panel 100.

After setting the cutting line 1000 c or at the same time, a bendingline 1000 f can be set on the mother substrate 1000. The bending line1000 f can be configured to form the bending portion 100 f describedabove in each display panel after the cells 1100 are separated from themother substrate 1000. Accordingly, the bending line 1000 f can be setbetween non-folding portion forming regions 1001 and 1002 that will formnon-folding portions after the cells 1100 are separated.

FIG. 16 is a diagram illustrating a manufacturing process of the displaypanel according to the first embodiment, and is a cross-sectional viewtaken along line A-A′ in FIG. 15 .

Referring to FIG. 16 , a method of cutting the mother substrate 1000according to the cutting line 1000 c will be described. Referring to (a)of FIG. 16 , an organic film 12 is formed on a mother glass substrate1110, which is a glass substrate that has not yet been cut. The organicfilm 12 includes a cell organic film disposed on each of the cells 1100and a cutting line organic film disposed in the cutting line 1000 cregion. The cell organic film and the cutting line organic film are onefilm connected to each other. For example, the organic film 12 can beformed by entirely coating an organic material on the mother glasssubstrate 1110. As described above, the circuit layer 14 is formed onthe organic film 12 and the light emitting element layer 16 is formed onthe circuit layer 14. An encapsulation layer 18 is formed on theemitting element layer, and a polarizing plate 20 is formed on theencapsulation layer 18. The polarizing plate 20 can be bent and extendedat an edge region except for a region where pads connected to anexternal circuit are formed, and be in contact with the upper surface ofthe organic film 12. Here, the polarizing plate 20 can be a coatedpolarizing plate formed by a coating method, but is not limited theretoand can be a film-type polarizing plate. An adhesive 19 can be appliedbetween the polarizing plate 20 and the encapsulation layer 18.

Thereafter, a mask 1120 can be formed on the rear surface of the motherglass substrate 1110. The mask 1120 can expose the mother glasssubstrate 1110 at the cutting line 1000 c. In other words, the mask 1120can include an aperture hole exposing the mother glass substrate 1110 atthe cutting line 1000 c.

The mother glass substrate 1110 can be wet-etched by supplying anetchant to the aperture hole formed in the mask 1120 formed on the rearsurface of the mother glass substrate 1110. The organic film 12 disposedon the mother glass substrate 1110 prevents the etchant from penetratinginto the circuit layer 14. For example, the organic film 12 can serve asan etch stopper. As the etchant, a hydrofluoric acid-based etchant canbe used, but the present disclosure is not limited thereto.

Referring to (b) of FIG. 16 , after etching the mother glass substrate1110 near the cutting line 1000 c, the mask 1120 can be removed from themother glass substrate 1110. And then, a coating layer 30 can be formedon the rear surface of the mother glass substrate 1110. After that, eachcell 1100 can be separated from the mother substrate 1000 by irradiatinglaser light to layers (e.g., a polarizing plate 20, an organic film 12and a coating layer 30) located on the cutting line 1000 c. When a coverwindow 22 is formed on the polarizing plate 20, the display panel 100can be completed as shown in (c) of FIG. 16 .

FIG. 17 is a diagram illustrating a manufacturing process of the displaypanel according to the first embodiment, and is a cross-sectional viewtaken along line B-B′ in FIG. 15 .

Referring to FIG. 17 , a method of etching a part of the mother glasssubstrate 1110 along the bending line 1000 f set on the mother substrate1000 will be described. As described above, the reason for etching themother glass substrate 1110 in a region of the bending line 1000 f is tofacilitate bending.

Referring to (a) of FIG. 17 , the mask 1120 can be formed on the rearsurface of the mother glass substrate 1110. The mask 1120 can expose themother glass substrate 1110 through the bending line 1000 f. In otherwords, the mask 1120 can include an aperture hole exposing the motherglass substrate 1110 from the bending line 1000 f.

The mother glass substrate 1110 can be wet etched by supplying anetchant to the aperture hole formed in the mask 1120 formed on the rearsurface of the mother glass substrate 1110. The organic film 12 arrangedon the mother glass substrate 1110 prevents the etchant from penetratinginto the circuit layer 14. For example, the organic film 12 can serve asan etch stopper. As the etchant, a hydrofluoric acid-based etchant canbe used, but the present disclosure is not limited thereto.

Referring to (b) of FIG. 17 , after etching the mother glass substrate1110 near the bending line 1000 f, the mask 1120 can be removed from themother glass substrate 1110, a coating layer 30 can be formed on therear surface of the mother glass substrate 1110, and a cover window 22can be formed on the polarizing plate 20.

The mask 1120 exposing the mother glass substrate 1110 in the cuttingline 1000 c and the bending line 1000 f is the same mask, and can beformed by the same process. In addition, the process of etching themother glass substrate 1110 in the cutting line 1000 c and the bendingline 1000 f is the same process and can be performed simultaneously.

FIG. 18 is a diagram illustrating a manufacturing process of a displaypanel according to the second embodiment, and is a cross-sectional viewtaken along line A-A′ in FIG. 15 . FIG. 20 is a cross-sectional viewtaken along line C-C′ in FIG. 15 .

With reference to FIGS. 18 and 20 , a method of cutting the mothersubstrate 1000 according to the second embodiment along the cutting line1000 c will be described.

Referring to (a) of FIG. 18 , a protective organic film 13-2 is formedon a mother glass substrate 1110, which is a glass substrate that hasnot yet been cut. Referring to FIG. 20 , the protective organic film13-2 can be formed in a boundary region between the cell 1100 and thecell 1100. The circuit layer 14 is formed on the mother glass substrate1110, and the light emitting element layer 16 is formed on the circuitlayer 14. The encapsulation layer 18 is formed on the emitting elementlayer, and the polarizing plate 20 is formed on the encapsulation layer18. The adhesive 19 can be applied between the polarizing plate 20 andthe encapsulation layer 18. The polarizing plate 20 can be bent andextended at an edge region except for a region where pads connected toan external circuit are formed, and be in contact with the upper surfaceof the protective organic film 13-2.

Thereafter, the mask 1120 can be formed on the rear surface of themother glass substrate 1110. The mask 1120 can expose the mother glasssubstrate 1110 at the cutting line 1000 c. In other words, the mask 1120can include an aperture hole exposing the mother glass substrate 1110 inthe cutting line 1000 c.

The mother glass substrate 1110 can be wet etched by supplying anetchant to the aperture hole formed in the mask 1120 formed on the rearsurface of the mother glass substrate 1110. The protective organic film13-2 disposed on the mother glass substrate 1110 prevents the etchantfrom penetrating into the circuit layer 14. For example, the protectiveorganic film 13-2 can serve as an etch stopper. As the etchant, ahydrofluoric acid-based etchant can be used, but the present disclosureis not limited thereto.

Referring to (b) of FIG. 18 , after etching the mother glass substrate1110 near the cutting line 1000 c, the mask 1120 can be removed from themother glass substrate 1110, and a coating layer 30 can be formed on therear surface of the mother glass substrate 1110. After that, each cell1100 can be separated from the mother substrate 1000 by irradiatinglaser light to layers (e.g., the polarizing plate 20, the organic film12 and the coating layer 30) located on the cutting line 1000 c. Whenthe cover window 22 is formed on the polarizing plate 20, the displaypanel 100 can be completed as shown in (c) of FIG. 18 .

FIG. 19 is a diagram illustrating a manufacturing process of a displaypanel according to the second embodiment, and is a cross-sectional viewtaken along line B-B′ in FIG. 16 .

Referring to FIG. 19 , a method of etching a part of the mother glasssubstrate 1110 along the bending line 1000 f set in the mother substrate1000 will be described.

Referring to (a) of FIG. 19 , the second embodiment includes a partialorganic film 13-1 disposed on the mother glass substrate 1110. Thepartial organic film 13-1 can be formed over a portion of thenon-folding portion forming regions 1001 and 1002 and the bending line1000 f.

The mask 1120 can be formed on the rear surface of the mother glasssubstrate 1110. The mask 1120 can expose the mother glass substrate 1110in the bending line 1000 f. In other words, the mask 1120 can include anaperture hole exposing the mother glass substrate 1110 at the bendingline 1000 f.

The mother glass substrate 1110 can be wet etched by supplying anetchant to the aperture hole formed in the mask 1120 formed on the rearsurface of the mother glass substrate 1110. The partial organic film13-1 disposed on the mother glass substrate 1110 prevents the etchantfrom penetrating into the circuit layer 14. For example, the partialorganic film 13-1 can serve as an etch stopper. As the etchant, ahydrofluoric acid-based etchant can be used, but the present disclosureis not limited thereto.

Referring to (b) of FIG. 19 , after etching the mother glass substrate1110 near the bending line 1000 f, the mask 1120 is removed from themother glass substrate 1110, a coating layer 30 can be formed on a rearsurface of the mother glass substrate 1110, and a cover window 22 can beformed on the polarizing plate 20.

The mask 1120 exposing the mother glass substrate 1110 in the cuttingline 1000 c and the bending line 1000 f is the same mask, and can beformed by the same process. In addition, the process of etching themother glass substrate 1110 in the cutting line 1000 c and the bendingline 1000 f is the same process and can be performed simultaneously.

Since the display panel according to the third embodiment does not havethe partial organic film 13-1, it is manufactured in the same manner asin the second embodiment except that there is no process of etching themother glass substrate 1110 at the bending line 1000 f.

FIG. 20 is a cross-sectional view taken along line C-C′ in FIG. 15 .

Referring to FIG. 20 , the role of the protective organic film 13-2according to the embodiment will be described. When etching the motherglass substrate 1110 using wet etching, if there is no etch preventingfilm, for example, etch stopper, the etchant penetrates the circuitlayer 14 and the light emitting element layer 16 on the substrate, suchthat damage can be caused. When the organic film 12 is applied on theentire surface as in the first embodiment, it is not a problem becausethe organic film 12 can serve as an etch stopper. However, the partialorganic film 13-1 is used as in the second embodiment, or in the case ofa panel that does not use an organic film as in the third embodiment,the etchant penetrates the circuit layer 14 and the emitting elementlayer 16 in the etching process, such that damage can be caused. In theembodiments of the present disclosure, the above-described problem canbe prevented by providing a configuration capable of serving as an etchstopper such as the protective organic film 13-2 or the partial organicfilm 13-1 on the cutting line 1000 c to be etched.

In summary, the protective organic film 13-2 is configured to preventdamage due to the etchant flowing into the circuit layer 14 and thelight emitting element layer 16 in a wet etching process. In order toprevent the etchant from penetrating into the circuit layer 14 and thelight emitting element layer 16, it is formed on the cutting line 1000 cand can be disposed on the mother glass substrate 1110.

The protective organic film 13-2 can be a film including one selectedfrom the group consisting of a polyimide polymer, a polyester polymer, asilicone polymer, an acrylic polymer, a polyolefin polymer, and acopolymer thereof.

The protective organic film 13-2 can have a plurality of layers asneeded. In an embodiment, as shown in FIG. 20 , a first organic film13-2(a) and a second organic film 13-2(b) can be included. The firstorganic film 13-2(a) and the second organic film 13-2(b) can include thesame material as other layers on the display panel 100. For example, thesecond organic film 13-2(b) can be made of the same material as a bankon the display panel 100. However, the present disclosure is not limitedthereto, and any material including an organic material and capable ofserving as an etch stopper can be used.

Hereinafter, a method of etching the mother glass substrate 1110according to the embodiment will be described in more detail.

In the embodiment, a part of the mother glass substrate 1110 can beetched by a wet etching method to separate the cells 1100 disposed onthe glass mother substrate 1110 or to form a bending portion 100 f or abending line 1000 f In addition, in the embodiment, the mother glasssubstrate 1110 can be etched by a wet etching method in order to processthe sidewalls of the edge of the glass substrate 10 into a desiredshape.

FIG. 21 is a view showing the etching process of the mother glasssubstrate, viewed from the rear surface of the mother glass substrateupside down.

Referring to FIG. 21 , the mask 1120 can be disposed on one surface of amother glass substrate 1110, and etch preventing films 12 and 13-2 canbe disposed on the other surface of the mother glass substrate 1110. Thecircuit layer and the organic emission layer are disposed on the etchpreventing films 12 and 13-2, but are omitted for convenience ofdescription. The mask 1120 and the etch preventing film 50 can beorganic films applied or adhered to the mother glass substrate 1110. Theetch preventing films 12 and 13-2 can serve as an etch stopper in theetching process, and can be the organic film 12 or the protectiveorganic film 13-2 of the above-described embodiment. The mask 1120 caninclude an aperture hole exposing the glass by the etchant. The shape,thickness, spacing, and the like of the glass pattern can be determinedaccording to the shape and spacing of the aperture hole and the etchingprocess time. The mask 1120 can be removed after an etching process.

According to the present disclosure, the mother glass substrate 1110 canbe etched by spraying the etchant onto the mother glass substrate 1110to which the mask 1120 is bonded or by putting the mother glasssubstrate 1110 into a water tank containing the etchant by a deepingmethod.

A glass etchant is supplied to the mother glass substrate 1110 throughthe aperture hole of the mask 1120. The mother glass substrate 1110exposed to the aperture hole of the mask 1120 starts to be etched inresponse to the glass etchant as shown in (a) of FIG. 21 . As shown in(b) of FIG. 21 , the glass exposed to the etchant is etched to form anopening in the mother glass substrate 1110, and the depth of the openingincreases as the etching process time elapses, as shown in (c) of FIG.21 . When the etching process time is longer in the etching process, theetchant can penetrate between the mother glass substrate 1110 and theetch preventing film 50 and between the mother glass substrate 1110 andthe mask 1120 to form a tapered surface on the sidewall glass of theopening, as shown in (d) and (e) of FIG. 21 .

As the etching process time increases, the tapered surface begins toform on the edge of the mother glass substrate 1110 exposed to theetchant, and as the process time is further increased, the taperedsurface becomes longer. In the etching process, when the lower surfaceof the glass substrate 10 is exposed to the etchant, the thickness ofthe glass substrate 10 decreases and the tapered surface becomes longer.The etching process stops when reaching the design value of the glasssubstrate thickness and the wedge shape of the cross section.

FIG. 22 is a cross-sectional photograph of a tapered surface formed on asidewall of the glass substrate 10. FIG. 23 is a view showing variousexamples of a wedge-type sidewall of the glass substrate 10. FIG. 24 isa cross-sectional photograph of the glass substrate showing a taperedsurface when the thickness of the substrate is reduced by an etchingprocess of the glass substrate 10.

Referring to FIG. 22 , the sidewall of the glass substrate 10 caninclude a tapered surface. In other words, the thickness of the sidewallof the edge of the glass substrate 10 according to the embodiment can besmaller at the edge of the substrate than at the center of thesubstrate. For example, the thickness of the edge of the glass substrate10 can be inversely proportional to the distance from the center. Theshape of the sidewall of the edge of the substrate can be variouslyshown as in the embodiments shown in FIG. 22 . The embodiments shown inFIG. 22 have upper and lower asymmetric tapered surfaces with respect tothe thickness center of the glass substrate 10. The shape of the taperedsurface is not limited thereto, and can be vertically symmetrical withrespect to the center of the thickness of the glass substrate 10 asshown in FIGS. 23 and 24 .

Referring to FIGS. 23 and 24 , the wedge-type sidewall of the glasssubstrate 10 has a vertically symmetric tapered surface 10 w withrespect to center REF of the thickness of the glass substrate 10. Asshown in the photograph of FIG. 24 , as the thickness of the glasssubstrate 10 decreases, the length L of the tapered surface 10 w canincrease. In other words, the length L of the tapered surface 10 w canbe in inverse proportion to the thickness of the glass substrate 10.

FIG. 25 is a block diagram illustrating an example of a display deviceaccording to an embodiment of the present disclosure. FIG. 26 is a blockdiagram illustrating an example of a display device according to anotherembodiment of the present disclosure. FIGS. 27A and 27B are viewsshowing an example in which the display device illustrated in FIG. 26 isfolded. FIG. 28 is a block diagram schematically showing theconfiguration of a drive IC.

In the display device shown in FIG. 25 , the display panel 100 can befolded around the bending portion 100 f between first and second regions101 and 102. The first region 101 includes a pixel array of a screen onwhich an image is reproduced. The second region 102 does not include apixel array. The drive IC 300 can be mounted on the second region 102,and the second region 102 can be folded behind the first region 101.

In the display device shown in FIG. 26 , the display panel 100 includesnon-bending portions 101 and 102 that are folded around the bendingportion 100 f. In the display panel 100, the bending portion 100 f andthe non-bending portions 101 and 102 can include a pixel array in whichan input image is reproduced. As shown in FIG. 25 , in the displaydevice, when the display panel 100 is unfolded, the entire screen of thedisplay panel 100 can be activated to display an image on the maximumscreen. When the display panel 100 is folded, a part of the screen canbe activated to display an image on an active region smaller than themaximum screen, and a black color can be displayed on an inactive regionor a previous image can be maintained.

Referring to FIGS. 25 to 28 , the display device includes a displaypanel 100 in which a pixel array is disposed on a screen, and a displaypanel driver.

The pixel array of the display panel 100 includes pixels P arranged in amatrix form defined by data lines DL, gate lines GL intersected with thedata lines DL, and data lines DL and gate lines GL. The structure of thedisplay panel 100 includes a circuit layer and a light emitting elementlayer stacked on the glass substrate 10 as in the above-describedembodiments. The light emitting element layer includes a light emittingelement of the pixel circuit.

The display panel 100 illustrated in FIG. 26 can be folded in anin-folding method illustrated in FIG. 27A or an out-folding methodillustrated in FIG. 27B. In the in-folding method, the screen on whichthe image is displayed is the inner surface that is folded in thedisplay panel 100. Accordingly, when the display panel 100 is folded inthe in-folding method, the screen is not exposed to the outside. In theout-folding method, the display panel 100 is the outer surface in thescreen is exposed to the outside when the display panel 100 is folded asshown in FIG. 27B.

Each of the pixels P includes sub-pixels having different colors forcolor implementation. The sub-pixels include red (hereinafter referredto as “R sub-pixel”), green (hereinafter referred to as “G sub-pixel”),and blue (hereinafter referred to as “B sub-pixel”). Each of the pixelsP can further include a white sub-pixel. Hereinafter, a pixel can beinterpreted as a sub-pixel unless otherwise defined. Each of thesub-pixels can include a pixel circuit.

The pixel circuit can include a light emitting element, a drivingelement for supplying current to the light emitting element, a pluralityof switch devices for programming a conduction condition of the drivingdevice and switching current paths between the driving element and thelight emitting element, and a capacitor for maintaining the gate voltageof the driving element, and the like.

The display panel driver writes the pixel data of the input image to thepixels P. The display panel driver includes a data driver 306 forsupplying a data voltage of pixel data to the data lines DL, and a gatedriver 120 for sequentially supplying a gate pulse to the gate lines GL.The data driver 306 can be integrated in the drive IC 300.

The drive IC 300 can be attached to the display panel 100. The drive IC300 receives pixel data of an input image and a timing signal from thehost system 200, supplies a data voltage of the pixel data to thepixels, and synchronizes the data driver 306 and the gate driver 120.

The drive IC 300 is connected to the data lines DL1 to DL6 through dataoutput channels to supply a voltage of a data signal to the data lines.The drive IC 300 can output a gate-timing signal for controlling thegate driver 120 through gate timing signal output channels. The gatetiming signal generated from the timing controller 303 can include aGate start pulse (VST), a Gate shift clock (CLK), and the like. Thestart pulse VST and the shift clock CLK swing between the gate-onvoltage VGL and the gate-off voltage VGH. The gate timing signals VSTand CLK output from the level shifter 307 are applied to the gate driver120 to control a shift operation of the gate driver 120.

The gate driver 120 can include a shift register formed in the circuitlayer of the display panel 100 together with the pixel array. The shiftregister of the gate driver 120 sequentially supplies the gate signal tothe gate lines GL under the control of the timing controller. The gatesignal can include a scan pulse and an EM pulse of the light emittingsignal. The shift register can include a scan driver for outputting ascan pulse and an EM driver for outputting an EM pulse. In FIG. 27 ,GVST and GCLK are gate-timing signals input to the scan driver. EVST andECLK are gate-timing signals input to the EM driver.

The drive IC 300 can be connected to the host system 200, a first memory301, and the display panel 100. The drive IC 300 can include a datareception and operation unit 308, a timing controller 303, a data driver306, a gamma compensation voltage generator 305, a power supply unit304, a second memory 302, and the like.

The data reception and operation unit 308 includes a receiver forreceiving pixel data input as a digital signal from the host system 200and a data operation unit for improving image quality by processing thepixel data input through the receiver. The data operation unit caninclude a data restoration unit that decodes and restores compressedpixel data, an optical compensation unit that adds a preset opticalcompensation value to the pixel data, and the like. The opticalcompensation value can be set as a value for correcting the luminance ofeach pixel data based on the luminance of the screen measured based onthe camera image captured in the manufacturing process.

The timing controller 303 provides pixel data of an input image receivedfrom the host system 200 to the data driver 306. The timing controller303 generates a gate-timing signal for controlling the gate driver 120and a source-timing signal for controlling the data driver 306 tocontrol the operation timing of the gate driver 120 and the data driver306.

The data driver 306 converts the pixel data (digital signal) receivedfrom the timing controller 303 through a digital-to-analog converter(hereinafter referred to as “DAC”) into a gamma compensation voltage tooutput a data signal DATA1 to DATA6) (hereinafter referred to as “datavoltage”). The data voltage output from the data driver 306 is suppliedto the data lines DL1 to DL6 of the pixel array through an output buffer(Source AMP) connected to the data channel of the drive IC 300.

The gamma compensation voltage generator 305 divides a gamma referencevoltage from the power supply unit 304 through a voltage divider circuitto generate a gamma compensation voltage for each gray level. The gammacompensation voltage is an analog voltage in which a voltage is set foreach gray level of pixel data. The gamma compensation voltage outputfrom the gamma compensation voltage generator 305 is provided to thedata driver 306.

The power supply unit 304 generates power required for driving the pixelarray of the display panel 100, the gate driver 120, and the drive IC300 using a DC-DC converter. The DC-DC converter can include a chargepump, a regulator, a buck converter, a boost converter, and the like.The power supply unit 304 can adjust the DC input voltage from the hostsystem 200 to generate DC power such as a gamma reference voltage, agate-on voltage VGL, a gate-off voltage VGH, a pixel driving voltageELVDD, a low potential power voltage ELVSS, an initialization voltageVini, and the like. The gamma reference voltage is supplied to a gammacompensation voltage generator 305. The gate-on voltage VGL and thegate-off voltage VGH are supplied to a level shifter 307 and the gatedriver 120. The pixel power such as the pixel driving voltage ELVDD, thelow potential power voltage ELVSS, and the initialization voltage Vini,and the like is commonly supplied to the pixels P. The initializationvoltage Vini is set to a DC voltage lower than the pixel driving voltageELVDD and lower than the threshold voltage of the light emitting elementOLED to suppress light emission of the light emitting element OLED.

The second memory 302 stores a compensation value, register settingdata, and the like, received from the first memory 301 when the power isinput to the drive IC 300. The compensation value can be applied tovarious algorithms that have improved image quality. The compensationvalue can include an optical compensation value. The register settingdata defines operations of the data driver 306, the timing controller303, the gamma compensation voltage generator 305, and the like. Thefirst memory 301 can include a flash memory. The second memory 302 caninclude static RAM (SRAM).

The host system 200 can be implemented as an application processor (AP).The host system 200 can transmit pixel data of an input image to thedrive IC 300 through a mobile Industry Processor Interface (MIPI). Thehost system 200 can be connected to the drive IC 300 through a flexibleprinted circuit (FPC), for example.

The host system 200 can detect the folding and unfolding states of thedisplay panel 100 shown in FIG. 25 and sense a folding angle using asensor.

In the display device of the present disclosure, the pixel circuit andthe gate driver can include a plurality of transistors. The transistorscan be implemented as an oxide thin film transistor (TFT) including anoxide semiconductor, an LTPS TFT including a low temperature polysilicon (LTPS), and the like. Each of the transistors can be implementedas a p-channel TFT or an n-channel TFT. In the embodiment, thedescription will be focused on an example in which the transistors ofthe pixel circuit are implemented as a p-channel TFT, but the presentdisclosure is not limited thereto.

A transistor is a three-electrode device including a gate, a source, anda drain. The source is an electrode that supplies carriers to thetransistor. In the transistor, the carriers begin to flow from thesource. The drain is an electrode through which carriers exit thetransistor. In a transistor, the flow of carriers flows from the sourceto the drain. In the case of an n-channel transistor, the source voltageis lower than the drain voltage so that electrons can flow from thesource to the drain because the carriers are electrons. In an re-channeltransistor, current flows from the drain to the source. In the case of ap-channel transistor (PMOS), since carriers are holes, the sourcevoltage is higher than the drain voltage so that holes can flow from thesource to the drain. In a p-channel transistor, current flows from thesource to the drain because holes flow from the source to the drain. Itshould be noted that the source and drain of the transistor are notfixed. For example, the source and drain can be changed according to anapplied voltage. Accordingly, the present disclosure is not limited bythe source and drain of the transistor. In the following description,the source and drain of the transistor will be referred to as first andsecond electrodes.

The gate pulse swings between a gate-on voltage and a gate-off voltage.The gate-on voltage is set to a voltage higher than the thresholdvoltage of the transistor, and the gate-off voltage is set to a voltagelower than the threshold voltage of the transistor. The transistor isturned on in response to the gate-on voltage, while it is turned off inresponse to the gate-off voltage. In the case of an n-channeltransistor, the gate-on voltage can be a gate high voltage (VGH), andthe gate-off voltage can be a gate low voltage (VGL). In the case of thep-channel transistor, the gate-on voltage can be the gate low voltageVGL, and the gate-off voltage can be the gate high voltage VGH.

The driving element in each of the pixels can be implemented as atransistor. Although the driving element should have uniform electricalcharacteristics among all pixels, there can be differences betweenpixels due to process deviation and element characteristics deviationand can change with the lapse of display driving time. In order tocompensate for the deviation in the electrical characteristics of thedriving element, the display device can include an internal compensationcircuit and an external compensation circuit. The internal compensationcircuit is added to the pixel circuit in each of the sub-pixels tosample the threshold voltage Vth and/or mobility μ of the drivingelement, which change according to the electrical characteristics of thedriving element, and compensate for the change in real time. Theexternal compensation circuit transmits a threshold voltage and/ormobility of a driving element sensed through a sensing line connected toeach of the sub-pixels to an external compensation unit. Thecompensation unit of the external compensation circuit compensates forthe change in the electrical characteristics of the driving element bymodulating the pixel data of the input image by reflecting the sensingresult. By sensing a voltage of a pixel that changes according to anelectrical characteristic of an external compensation-driving element,and modulating data of an input image in an external circuit based onthe sensed voltage, the deviation in the electrical characteristic ofthe driving element between pixels is compensated.

FIG. 29 is a circuit diagram showing an example of a pixel circuit. FIG.30 is a diagram illustrating a method of driving the pixel circuit shownin FIG. 29 . The pixel circuit applicable to the present disclosure isnot limited to FIGS. 29 and 30 .

Referring to FIGS. 29 and 30 , the pixel circuit includes a lightemitting element OLED, a driving element DT for supplying current to thelight emitting element OLED, and an internal compensation circuit forcompensating for the gate voltage of the driving element DT by thethreshold voltage Vth of the driving element DT, by using a plurality ofswitch elements M1 to M6 and sampling the threshold voltage Vth of thedriving element DT. Each of the driving element DT and the switchelements M1 to M6 can be implemented as a p-channel TFT.

The driving period of the pixel circuit using the internal compensationcircuit can be divided into an initialization period Tini, a samplingperiod Tsam, a data-writing period Twr, and a light emitting period Tem.

During the initialization period Tini, the N−1-th scan signal SCAN(N−1)is generated as a pulse of the gate-on voltage VGL, and a voltage ofeach of the N-th scan signal SCAN(N) and the light emitting signal EM(N)is the gate-off voltage VGH. During the sampling period Tsam, the N-thscan signal SCAN(N) is generated as a pulse of the gate-on voltage VGL,and a voltage of each of the N-lth scan signal SCAN(N−1) and the lightemitting signal EM(N) is the gate-off voltage VGH. During thedata-writing period Twr, a voltage of each of the N-lth scan signalSCAN(N−1), the Nth scan signal SCAN(N), and the light emitting signalEM(N) is the gate-off voltage VGH. During at least a part of the lightemitting period Tem, the light emitting signal EM(N) is generated as thegate-on voltage VGL, and a voltage of each of the N−1 scan signalSCAN(N−1) and the N-th scan signal SCAN(N) is generated as the gate-offvoltage VGH.

During the initialization period Tin, the fifth and sixth switchelements M5 and M6 are turned on according to the gate-on voltage VGL ofthe N-lth scan signal SCAN(N−1) to initialize the pixel circuit. Duringthe sampling period Tsam, the first and second switch elements M1 and M2are turned on according to the gate-on voltage VGL of the N-th scansignal SCAN(N), such that the threshold voltage of the driving elementDT is sampled and stored in the capacitor Cst. During the data-writingperiod Twr, the first to sixth switch elements M1 to M6 maintain an offstate. During the light emitting period Tem, the third and fourth switchelements M3 and M4 are turned on to emit light from the light emittingelement OLED. During the light emitting period Tem, in order toprecisely express the luminance of the low gray level with the dutyratio of the light emitting signal EM(N), the light emitting signalEM(N) swings at a predetermined duty ratio between the gate-on voltageVGL and the gate-off voltage VGH, so that the third and fourth switchelements M3 and M4 are turned on/off repeatedly.

The light emitting element OLED can be implemented as an organic lightemitting diode or as an inorganic light emitting diode. Hereinafter, anexample in which the light emitting element OLED is implemented as anorganic light emitting diode will be described.

The light emitting element OLED can include an organic compound layerformed between an anode and a cathode. The organic compound layerincludes a hole injection layer (HIL), a hole transport layer (HTL), anemission layer (EML), an electron transport layer (ETL) and an electroninjection layer (EIL), but is not limited thereto. When a voltage isapplied to the anode and cathode of the OLED, holes passing through thehole transport layer (HTL) and electrons passing through the electrontransport layer (ETL) are moved to the emission layer (EML), such thatexcitons are formed, and visible light is emitted from the emissionlayer (EML).

The anode of the light emitting element OLED is connected to the fourthnode n4 between the fourth and sixth switch elements M4 and M6. Thefourth node n4 is connected to the anode of the light emitting elementOLED, the second electrode of the fourth switch element M4, and thesecond electrode of the sixth switch element M6. The cathode of thelight emitting element OLED is connected to a VSS electrode PL3 to whichthe low potential power voltage VSS is applied. The light emittingelement OLED emits light with a current Ids flowing according to thegate-source voltage Vgs of the driving element DT. The current path ofthe light emitting element OLED is switched by the third and fourthswitch elements M3 and M4.

The storage capacitor Cst is connected between the VDD line PL1 and thefirst node n1. The data voltage Vdata compensated by the thresholdvoltage Vth of the driving element DT is charged in the storagecapacitor Cst. Since the data voltage Vdata in each of the sub-pixels iscompensated by the threshold voltage Vth of the driving element DT, thecharacteristic deviation of the driving element DT in the sub-pixels iscompensated.

The first switch element M1 is turned on in response to the gate-onvoltage VGL of the N-th scan pulse SCAN(N) to connect the second node n2and the third node n3. The second node n2 is connected to the gate ofthe driving element DT, the first electrode of the storage capacitorCst, and the first electrode of the first switch element M1. The thirdnode n3 is connected to the second electrode of the driving element DT,the second electrode of the first switch element M1, and the firstelectrode of the fourth switch element M4. A gate of the first switchelement M1 is connected to the first gate line GL1 to receive the N-thscan pulse SCAN(N). A first electrode of the first switch element M1 isconnected to the second node n2, and a second electrode of the firstswitch element M1 is connected to the third node n3.

The second switch element M2 is turned on in response to the gate-onvoltage VGL of the N-th scan pulse SCAN(N) to supply the data voltageVdata to the first node n1. A gate of the second switch element M2 isconnected to the first gate line GL1 to receive the N-th scan pulseSCAN(N). A first electrode of the second switch element M2 is connectedto the first node n1. A second electrode of the second switch element M2is connected to the data line DL to which the data voltage Vdata isapplied. The first node n1 is connected to the first electrode of thesecond switch element M2, the second electrode of the third switchelement M3, and the first electrode of the driving element DT.

The third switch element M3 is turned on in response to the gate-onvoltage VGL of the light emitting signal EM(N) to connect the VDD linePL1 to the first node n1. A gate of the third switch element M3 isconnected to the third gate line GL3 to receive the light emittingsignal EM(N). A first electrode of the third switch element M3 isconnected to the VDD line PL1. A second electrode of the third switchelement M3 is connected to the first node n1.

The fourth switch element M4 is turned on in response to the gate-onvoltage VGL of the light emitting signal EM(N) to connect the third noden3 to the anode of the light emitting element OLED. A gate of the fourthswitch element M4 is connected to the third gate line GL3 to receive thelight emitting signal EM(N). A first electrode of the fourth switchelement M4 is connected to the third node n3, and a second electrode ofthe fourth switch element M4 is connected to the fourth node n4.

The fifth switch element M5 is turned on in response to the gate-onvoltage VGL of the N−1-th scan pulse SCAN(N−1) to connect the secondnode n2 to the Vini line PL2. The gate of the fifth switch element M5 isconnected to the second gate line GL2 to receive the N-lth scan pulseSCAN(N−1). A first electrode of the fifth switch element M5 is connectedto the second node n2, and a second electrode of the fifth switchelement M5 is connected to the Vini line PL2.

The sixth switch element M6 is turned on in response to the gate-onvoltage VGL of the N−1-th scan pulse SCAN(N−1) to connect the Vini linePL2 to the fourth node n4. The gate of the sixth switch element M6 isconnected to the second gate line GL2 to receive the N-lth scan pulseSCAN(N−1). A first electrode of the sixth switch element M6 is connectedto the Vini line PL2, and a second electrode of the sixth switch elementM6 is connected to the fourth node n4.

The driving element DT controls the current Ids flowing through thelight emitting element OLED according to the gate-source voltage Vgs todrive the light emitting element OLED. The driving element DT includes agate connected to the second node n2, a first electrode connected to thefirst node n1, and a second electrode connected to the third node n3.

During the initialization period Tini, the N-lth scan pulse SCAN(N−1) isgenerated as the gate-on voltage VGL. The N-th scan pulse SCAN(N) andthe light emitting signal EM(N) maintain the gate-off voltage VGH duringthe initialization period Tini. Accordingly, during the initializationperiod Tini, the fifth and sixth switch elements M5 and M6 are turnedon, so that the second and fourth nodes n2 and n4 are initialized toVini. A hold period Th can be set between the initialization period Tiniand the sampling period Tsam. In the hold period Th, the gate pulsesSCAN(N−1), SCAN(N), and EM(N) maintain the previous state.

During the sampling period Tsam, the N-th scan pulse SCAN(N) isgenerated as the gate-on voltage VGL. The pulse of the Nth scan pulseSCAN(N) is synchronized with the data voltage Vdata of the Nth pixelline. The N-lth scan pulse SCAN(N−1) and the light emitting signal EM(N)maintain the gate-off voltage VGH during the sampling period Tsam.Accordingly, the first and second switch elements M1 and M2 are turnedon during the sampling period Tsam.

During the sampling period Tsam, the gate voltage DTG of the drivingelement DT is increased by the current flowing through the first andsecond switch elements M1 and M2. Since the driving element DT is turnedoff when the driving element DT is turned off, the gate node voltage DTGis Vdata−|Vth|. In this case, the voltage of the first node n is alsoVdata−|Vth|. In the sampling period Tsam, the gate-source voltage Vgs ofthe driving element DT is |Vgs|=Vdata−(Vdata−|Vth|)=|Vth|.

During the data-writing period Twr, the N-th scan pulse SCAN(N) isinverted to the gate-off voltage VGH. The N-lth scan pulse SCAN(N−1) andthe light emitting signal EM(N) maintain the gate-off voltage VGH duringthe data writing period Twr. Accordingly, all the switch elements M1 toM6 maintain an off state during the data writing period Twr.

During the light emitting period Tem, the light emitting signal EM(N)can be generated as a gate-off voltage VGH. During the light emittingperiod Tem, in order to improve expression power of a low gray level,the light emitting signal EM(N) can be turned on/off with apredetermined duty ratio to be swung between the gate-on voltage VGL andthe gate-off voltage VGH. Accordingly, the light emitting signal EM(N)can be generated as the gate-on voltage VGL during at least a part ofthe light emitting period Tem.

When the light emitting signal EM(N) is the gate-on voltage VGL, currentflows between the ELVDD and the light emitting element OLED, so that thelight emitting element OLED can emit light. During the light emittingperiod Tem, the N−1-th and N-th scan pulses SCAN(N−1) and SCAN(N)maintain the gate-off voltage VGH. During the light emitting period Tem,the third and fourth switch elements M3 and M4 are repeatedly turnedon/off according to the voltage of the light emitting signal EM. Whenthe light emitting signal EM(N) is the gate-on voltage VGL, the thirdand fourth switch elements M3 and M4 are turned on, so that currentflows through the light emitting element OLED. In this case, Vgs of thedriving element DT is |Vgs|=ELVDD−(Vdata−|Vth|), and the current flowingthrough the light emitting element OLED is K(ELVDD−Vdata)2. K is aconstant value determined by the charge mobility, parasitic capacitance,and channel capacitance of the driving element (DT).

FIG. 31 is a cross-sectional view showing in detail a cross-section of adisplay panel 100 according to an embodiment of the present disclosure.It should be noted that the cross-sectional structure of the displaypanel 100 shown in FIG. 31 is only an example, and the presentdisclosure is not limited thereto.

Referring to FIG. 31 , a circuit layer, a light emitting element layer,an encapsulation layer, and the like can be stacked on the glasssubstrate GLS as described above.

A first buffer layer BUF1 can be formed on the glass substrate GLS. Afirst metal layer LC can be formed on the first buffer layer BUF1, and asecond buffer layer BUF2 can be formed on the first metal layer LS. Eachof the first and second buffer layers BUF1 and BUF2 can be formed of aninorganic insulating material and can be made of one or more insulatinglayers. The first metal layer LS can include a metal pattern disposedunder the TFT to block light irradiated to the semiconductor channellayer of the TFT.

An active layer ACT can be formed on the first buffer layer BUF2. Theactive layer ACT includes semiconductor patterns of TFTs of a pixelcircuit and TFTs of a gate driver, respectively. When the TFT isimplemented as an oxide TFT, the semiconductor pattern can includeindium gallium zinc oxide (IGZO).

A gate-insulating layer GI can be formed on the active layer ACT. Thegate insulating film GI is an insulating layer made of an inorganicinsulating material. A second metal layer GATE can be formed on thesecond gate-insulating layer GI. The second metal layer GATE can includea gate electrode of the TFT and a gate line connected to the gateelectrode.

A first interlayer insulating film ILD1 can cover the second metal layerGATE. A third metal layer TM can be formed on the first interlayerinsulating film ILD2, and the second interlayer insulating film ILD2 cancover the third metal layer TM. The capacitor Cst of the pixel circuitcan be formed in a portion where the second metal layer GATE, the firstinterlayer insulating film ILD1, and the third metal layer TM areoverlapped. The first and second interlayer insulating films ILD1 andILD2 can include an inorganic insulating material.

A fourth metal layer SD1 can be formed on the second interlayerinsulating film 1LD2, and an inorganic insulating film PAS1 and a firstplanarization layer PLN1 can be stacked thereon. A fifth metal layer SD2can be formed on the first planarization layer PLN2. A partial patternof the fifth metal layer SD2 can be connected to the fourth metal layerSD1 through a contact hole penetrating the first planarization layerPLN1 and the inorganic insulating film PAS1. The first and secondplanarization layers PLN1 and PLN2 are made of an organic insulatingmaterial for flattening surfaces.

The fourth metal layer SD1 can include first and second electrodes ofthe TFT connected to the semiconductor pattern of the TFT through acontact hole penetrating the second interlayer insulating film 1LD2. Thedata line DL and the power lines PL1 and PL2 can be implemented bypatterning the fourth metal layer SD1 or the fifth metal layer SD2.

An anode electrode AND of the light emitting element OLED can be formedon the second planarization layer PLN2. The anode electrode AND can beconnected to an electrode of a TFT used as a switch element or a drivingelement through a contact hole passing through the second planarizationlayer PLN2. The anode electrode AND can be formed of a transparent orsemi-transparent electrode material.

A pixel defining film BNK can cover the anode electrode AND of the lightemitting element OLED. The pixel defining film BNK is formed in apattern defining a light emitting region (or an opening region) throughwhich light passes from each of the pixels to the outside. A spacer SPCcan be formed on the pixel defining film BNK. The pixel defining filmBNK and the spacer SPC can be integrated with the same organicinsulating material. The spacer SPC secures a gap between the FMM andthe anode AND so that a fine metal mask (FMM) does not come into contactwith the anode AND during the deposition process of the organic compoundEL.

An organic compound EL is formed in a light emitting region of each ofthe pixels defined by the pixel defining film BNK. A cathode electrodeCAT of the light emitting element OLED is formed on the front surface ofthe display panel 100 to cover the pixel defining film BNK, the spacerSPC, and the organic compound EL. The cathode electrode CAT can beconnected to the VSS electrode PL3 formed of any one of the lower metallayers. A capping layer CPL can cover the cathode electrode CAT. Thecapping layer CPL protects the cathode electrode CAT by blockingpenetration of air and out-gassing of the organic insulating materialapplied on the capping layer CPL as the cathode electrode CAT is formedof the inorganic insulating material. The inorganic insulating layerPAS2 can cover the capping layer CPL, and a planarization layer PCL canbe formed on the inorganic insulating layer PAS2. The planarizationlayer PCL can include an organic insulating material. An inorganicinsulating layer PAS3 of the encapsulation layer can be formed on theplanarization layer PCL.

The above-described embodiments of the present disclosure can be appliedalone or in combination.

The above description of various embodiments does not specify essentialfeatures of claims, the scope of claims is not limited to mattersdescribed in the present disclosure.

While embodiments of the present disclosure have been described indetail above with reference to the accompanying drawings, the presentdisclosure is not necessarily limited to these embodiments, and variouschanges and modifications can be made without departing from the subjectmatter of the present disclosure. Accordingly, the embodiments disclosedherein are to be considered descriptive and not restrictive of thesubject matter of the present disclosure, and the scope of the subjectmatter of the present disclosure is not limited by these embodiments.Therefore, the above-described embodiments should be understood to beexemplary and not limiting in any aspect. The scope of the presentdisclosure should be construed by the appended claims, and all subjectmatters within the scopes of their equivalents should be construed asbeing included in the scope of the present disclosure.

What is claimed is:
 1. A mother substrate comprising: a glass substrateincluding a bending portion and a non-bending portion in a regiondefined by cutting lines adjacent to each other of a plurality ofcutting lines; an organic film overlapping the plurality of cuttinglines on the glass substrate; and a plurality of cells spaced apart fromeach other with each of the plurality of cutting lines therebetween onthe glass substrate, wherein the glass substrate includes an openingconfigured to expose a portion of the organic film in the bendingportion.
 2. The mother substrate of claim 1, wherein the organic filmoverlaps the plurality of cells and the plurality of cutting lines. 3.The mother substrate of claim 2, wherein the glass substrate furtherincludes at least one bending line disposed on each of the plurality ofcells, and the organic film includes a first organic film disposed onthe glass substrate to overlap a cutting line between neighbored cellsof the plurality of cells, and a second organic film disposed on theglass substrate to overlap the at least one bending line.
 4. The mothersubstrate of claim 1, wherein each of the plurality of cells comprises:a circuit layer disposed on the glass substrate to drive a pixel; alight emitting element layer including a first electrode on the circuitlayer, a bank disposed on the first electrode to define a light emittingarea, an organic compound layer on the first electrode in the lightemitting area, and a second electrode on the organic compound layer; anencapsulation layer covering the light emitting element layer; and apolarizing plate disposed on the encapsulation layer, and the organicfilm is disposed between the glass substrate and the circuit layer, andthe organic layer and the bank include a same material.
 5. The mothersubstrate of claim 4, wherein the organic film and the polarizing plateare sequentially stacked on the glass substrate between adjacent cellsto overlap the plurality of cutting lines.
 6. The mother substrate ofclaim 3, wherein the first and second organic films include a polyimidefilm.
 7. The mother substrate of claim 3, wherein the glass substrateincludes: a first opening exposing the first organic layer at positionsoverlapping the plurality of cutting lines; a second openings exposingthe second organic layer at positions overlapping the at least onebending line, and a coating layer is disposed on a rear surface of theglass substrate and at least a portion of the first and second openings.8. A display panel comprising: a glass substrate including a bendingportion and a non-bending portion; a circuit layer disposed on the glasssubstrate to drive a pixel; a light emitting element layer including alight emitting element which includes a first electrode on the circuitlayer, an organic compound layer on the first electrode, and a secondelectrode on the organic compound layer; an encapsulation layer coveringthe circuit layer and the light emitting element layer; a polarizingplate on the encapsulation layer; and an organic film on the glasssubstrate, wherein the glass substrate includes an opening configured toexpose a portion of the organic film in the bending portion.
 9. Thedisplay panel of claim 8, further comprising a bank disposed on thefirst electrode to define a light emitting area, wherein the organicfilm and the bank include a same material.
 10. The display panel ofclaim 8, further comprising at least one bending line for folding thedisplay panel, wherein the organic film includes a first organic film onedges of the glass substrate, and a second organic film disposed on theglass substrate to overlap the at least one bending line.
 11. Thedisplay panel of claim 10, wherein the glass substrate includes anopening exposing the second organic layer at a position overlapping theat least one bending line.
 12. The display panel of claim 11, wherein acoating layer is disposed on a rear surface of the glass substrate andat least a portion of the opening.
 13. The display panel of claim 8,wherein an edge sidewall of the glass substrate includes a wedge-shapedtapered surface, and a thickness of the sidewall becomes thinner as itgoes to the end of the sidewall.
 14. The display panel of claim 13,wherein the wedge-shaped tapered surface protrudes out of the circuitlayer.
 15. The display panel of claim 13, wherein a length of thewedge-shaped tapered surface is inversely proportional to a thickness ofthe glass substrate.
 16. A method of manufacturing a display panel froma plurality of cells disposed on a mother glass substrate having anorganic film, the method comprising: setting a cutting line betweenadjacent cells of the plurality of cells; forming a mask on one surfaceof the mother glass substrate to cover regions other than the cuttingline; etching the mother glass substrate exposed through the mask toform a first opening in the mother glass substrate; removing the mask;and cutting the organic film by irradiating a laser to the organic filmoverlapping the cutting line to separate the plurality of cells.
 17. Themethod of claim 16, wherein the setting the cutting line includessetting at least one bending line on which the display panel is foldedin each of the plurality of cells, and the forming the mask includes:forming the mask so that the mask does not cover the at least onebending line; and etching the mother glass substrate exposed through themask to form a second opening.
 18. The method of claim 17, wherein theorganic film includes: a first organic film disposed on the glasssubstrate to overlap a cutting line between neighbored cells of theplurality of cells; and a second organic film disposed on the motherglass substrate to overlap the at least one bending line.
 19. The methodof claim 16, further comprising: forming a coating layer on anothersurface of the mother glass substrate after removing the mask; andcutting the coating layer by irradiating the laser to the coating layerwhen the organic film is cut.
 20. The method of claim 16, wherein theetching the mother glass substrate is implemented by a wet etching.